PROCESS MONITOR

Abstract: A process monitor (10) for assessment of bending loads (70) encountered during mechanical handling of agricultural and manufactured products with a length (46) to diameter (47) ratio greater than 2:1, for example: sugar beet; has a core (12), and adjacent to a surface (40) piezo-electric plastic material cables (14) wound in a pattern (32, 34, 36, 38) sensitive to the particular processing conditions being monitored. The deflections (71) sustained by the envelope (20) of the process monitor (10) are used to identify situations where bending loads (70) occur which if applied to a real product would cause damage. After calibration against a real product the process monitor (10) is included in a batch of products to be processed. The deflections (71) experienced during handling especially those above a damaging threshold level (73) are monitored and logged within the process monitor (10). Rapid data analysis equipment (76) either external to or contained within the process monitor (10) is used to locate when and where the potentially damaging bending loads (70) occur.

Description: PROCESS MONITOR The present invention relates to process monitors for detection of damaging or potentially damaging processing conditions. In particular, it relates to the monitoring of processing conditions in which relatively high bending loads are likely to be applied, to inherently fragile elongate products, during mechanical handling. Process monitors according to the invention may be used in connection with agricultural products consisting of a body with a high length to diameter ratio such as sugar beet, carrots or parsnips. Alternatively, process monitors according to the invention may be used in connection with manufactured products with a high length to diameter ratio such as bottles or beer cans. For convenience, process monitors for use with agricultural products will be discussed herein. In modern agriculture many crops are subjected to a great deal of mechanical handling before reaching the market place. For example a cylindrical or conical root crop might be mechanically harvested, graded, and several times stored and then transferred to a transport system. During this processing a significant proportion of a crop may be damaged by bending to such an extent that it is not of merchantable quality when it reaches the market place. There is, therefore, continual interest in improving machinery to reduce in particular the bend loads applied. However, there is also an interest in increasing the speed of operation of the machinery, and the two interests may be contradictory. One of the problems in reduction of the damage caused by machinery is identification of the situations that actually cause damage, for example: collisions between two or more items of the crop, or collision between the crop and part of the machinery through which it is travelling; and where and when these events occur. Attempts to identify the nature and location of damaging situations occurring during mechanical processing of crops, have used simulated crops to monitor the processing, which are then subjected to the mechanical handling processes. Each process monitor has been designed to have physical characteristics such as shape and weight similar to those of the associated crop. These process monitors have contained either a pressure transducer or an accelerometer and either means for radio-telemetering or means for storing information for analysis. The scarcity of publications disclosing useful results leads to the conclusion that there are many unsolved difficulties in this field of technology. An example of a previously known process monitor is "Device for assessing processing stress" UK Patent GB 2196740 B, date of filing 22 Oct 1987. Devices according to GB 2196740 have produced successful results when used in conjunction with potato or apple crops, where it is desired to know only the surface pressures that the crops sustain during mechanical handling. Such devices have the disadvantage that they cannot assess the treatment of crops with an elongate body. These crops degrade when high bend loads are applied during mechanical handling of a relatively fragile crop. The process monitors made to the present invention differ from devices made to GB 2196740 in that in addition to responding surface pressures they respond to bending loads, that for example cause breakage in sugar beet crops. In the development of a process monitor that would successfully mimic the bend properties of for example sugar beet it was found that accurate replication of the stresses, or deflections actually induced in the sugar beet was not necessary. Neither was it necessary for the process monitor to have the same mechanical properties as sugar beet. On the contary the process monitor must be stronger than the sugar beet otherwise it would itself break in use. The invention teaches that the process monitor needs to act as a surrogate beet. Deflections, sustained by the surrogate beet or process monitor when subjected to bend forces, can be used to identify situations where bend forces occur, that if applied to a real sugar beet would exceed the bend strength of the sugar beet and cause it to break or snap. Before the process monitor can be used to locate when and where the potentially damaging bending loads occur it requires calibration by comparison with the performance of a sample of sugar beets in laboratory tests. The tests may be simple tests such as dropping a sample beet onto the surrogate beet. Observations of the reading displayed and the corresponding level of damage sustained by the sample beet, provide a library of information with which to interpret the readings obtained with the process monitor. According to the present invention the process monitor is a package having physical characteristics simulating those of a product whose surface is of substantially surface of revolution shape, and having at or adjacent to the surface of the package a layer of piezo-electric material which is connected to electronic processing equipment, characterised in that the surface of the package forms an envelope resembling a product with a length to diameter ratio greater than 2:1, the package being constructed so that deflections sustained by the envelope in response to bending loads can be used to identify the occurrence of bending loads which if applied to a product would cause damage. According to another aspect of the invention the layer of piezo-electric plastic material is divided into strips adjacent to the surface of the envelope. The strips and the envelope may be arranged so that deflection signals, corresponding to deflection of the envelope experiencing bending loads, are produced by the strips. These signals may be collected by the electronic processing equipment contained within the package. The strips may be arranged in random or in a distorted rectilinear pattern wrapped to conform with the surface of the envelope. Alternatively, the strips may be arranged in a quasi unidirectional pattern conforming with the surface of the envelope, the strips pointing in the direction of the axis of the envelope and extending along the surface of the envelope. Preferably, the strips may form helical coils conforming with the surface of the envelope. The selection of a particular pattern of strips will depend on the sensitivity required of process monitor in modelling the interaction between the product and the processing machinery through which it is travelling. In monitoring of sugar beet processing, the quasi unidirectional pattern is satisfactory, but the helical pattern provides a monitor that is more sensitive to the processing conditions. Strips in the form of piezo-electric plastic cables, that can be obtained commercially, have proved suitable for use in the invention. According to yet another aspect of the invention, the electronic processing equipment may be capable of being externally conditioned. Damaging deflection signals may be obtained when the deflections experienced by the envelope exceed a pre-selected deflection threshold. This will enable the identification of events likely to damage the crop being simulated. According to yet another aspect of the invention, processed deflection signals are transmitted from the electronic processing equipment to a data analysis means. The processed deflection signals may be compared with a library of calibration signals from the piezo-electric strips compiled by application of known bending loads to the package. The comparison providing an evaluation of the bending loads experienced by the package. According to yet another aspect of the invention, the package may store the deflection signals within the electronic processing equipment. The stored data may then be transmitted to the data analysis means after the package has been used to monitor the processing machinery. Likewise, the electronic processing equipment may be capable of storing and transmitting deflection signals gathered by the package during a number of encounters with the processing machinery. The deflection signals transmitted from the electronic processing equipment to the data analysis means may be one deflection level and a time. Alternatively, the deflection signals transmitted from the electronic processing equipment to the data analysis means may be a continuous record of deflection and time. According to yet another aspect of the invention the data analysis means may be a micro-computer, external to the package, programmed to compare the deflection signals from the piezo-electric strips with the library of calibration signals already stored in the micro-computer and to evaluate the bending loads applied to the package. The micro-computer may be connected to display means for displaying values and times relating to the processing environment experienced by the package. The data analysis means may be coupled directly by electrical or optical means to the electronic processing equipment. Sometimes it may be desirable for the data analysis means to be coupled by telemetry to the electronic processing equipment. In a alternative form of the invention, the data analysis means is contained within the package and is connectable to display means carried by the package for displaying deflection values and times relating to the processing environment experienced by the package. According to yet another aspect of the invention the material properties of the envelope in the direction of the longitudinal axis of the package may be chosen to permit deflection of the envelope when the package encounters bending loads. Additionally, the material properties of the envelope in a direction at right angles to the longitudinal axis of the package may be chosen so as to transmit bending loads applied to the envelope to the strips of piezo-electric material whether the bending loads are applied directly over the strips or not. According to yet another aspect of the invention the package may include a core with a substantially circular cross-section. The material properties of the core may be chosen so as to permit deflection of the envelope during the application of bending loads to the package. The strips of piezo-electric material may be placed at positions around an external circumferential surface of the core. The strips may be supported between the circumferential surface of the core and the internal surface of the envelope, to form a sandwich between the core and the envelope. Preferably, the package may include a core which is conical and similar in shape to the crop being simulated. Alternatively, the process monitor may include a core which is cylindrical and similar in shape to the crop being simulated. The weight an volume ( and therefore the density) of the package are preferably similar to those of the crop being simulated. The envelope is preferably waterproof and able to resist damage arising from normal handling and use as a process monitor but without damaging the crops with which it is processed. Advantageously, the envelope can be constructed from re-inforced plastics composite material. In particular, for the monitoring of sugar beet processing, the outer shape of the package may substantially conform to outer shape of a root of a sugar beet. Some embodiments of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, of which: Fig. 1 is an elevation, in section, of an embodiment of the invention, Fig. 2 is a cross section at Sl-Sl Fig.l, Fig. 3 is a cross section at S2-S2 Fig.l, Fig. 4 is a part perspective view showing a random pattern of piezo-electric plastic cables, Fig. 5 is a part perspective view showing a distorted rectilinear pattern piezo-electric plastic cables, Fig. 6 is a part perspective view showing a helical pattern of piezo-electric plastic cables, Fig. 7 is a part perspective view showing a unidirectional pattern of piezo-electric plastic cables. Fig. 8 is a block diagram of the data processing functions forming part of the invention. A process monitor 10 (Fig. 1, 2, 3 and 7), is shaped to resemble a sugar beet with length 46 and diameter 47 and is formed from a rigid plastic material. The process monitor includes a core 12, also conical in shape with a longitudinal axis 45. The core 12, is covered by ten piezo-electric plastic cables 14. The ends 16 of the cables 14, are connected to an electronic processing equipment 15 and electronic data storage 19, located in the space 18. The space 18 is formed in a cylindrical head piece 24 of the same material as the core 12, and joined to the core 12 with a bolt 21 and a nut 22. The nut 22 represents the point of the sugar beet root but is non-sensing. The conical shaped core 12, piezo-electric plastic cables 14 and head piece 24 are surrounded by an envelope 20 of reinforced plastic composite material material adapted to give the process monitor 10 physical characteristics corresponding to those of a sugar beet. Data output and battery charger connectors are positioned, on the process monitor 10, at 26 a region which is also non-sensing. The electronic processing equipment 15, can be connected for the purposes of data retrieval to: to an external data analysis unit usually a micro-computer 80; or to a data analysis unit 76 and display 17 carried by the process monitor 10 also positioned at 26. Referring to Fig 8, a portion of the envelope 20 is shown under the influence of a bending load 70. A deflection 71 relates to the bending load 70. Deflection signals 72 relating to the deflection 71 are produced by the layer of piezo-electric material 42. The deflection signals 72 are fed: either directly to the electronic processing equipment 15; or indirectly after triggering a pre-selected threshold deflection level 73. The deflection signals 72, or the damaging deflection signals 74, are stored in the solid state memory 19. Data may be retrieved from the solid state memory 19 in the form: of a one deflection 71 and a time as a discrete record 78; or a continuous record 79, of deflection 71 against time. The records 78 and 79, may be processed by the data analysis means 76 connected to a display 17 by comparison with a library of calibration signals 77. However, the micro-computer 80 connected to a display 81 and a library of calibration signals 77 is usually used for data analysis. The micro-computer 80 may be connected directly to the electronic processing equipment 15 by means of suitable cable or by telemetry (not shown). The use of the invention will now be described with reference to a process monitor 10, in which the electronic processing equipment 15 is adapted: to monitor deflection signals 72 above threshold deflection levels 73; and to store in the solid state memory 19 within the electronic processing equipment 15, a continuous record 79 of damaging deflections signals 74; and to store the times at which the threshold deflection 73 was exceeded. Before the process monitor 10 can be used it is connected to the micro-computer 80 and calibrated by comparison with the performance of a sample of sugar beets in laboratory tests. The tests are simple tests such as dropping a sample beet onto the process monitor 10. Observations of the display 81 and the corresponding level of damage sustained by the sample beet, provide a library of information 77 to be stored in the micro-computer 80. The process monitor 10 is then mixed with sugar beets and the mixture is passed through processing machinery (not shown) . After passing through the machinery the electronic processing equipment 15 is connected to a micro-computer 80, programmed to access processed signals 75. The processed signals 75 are then compared with the stored library of calibration signals 77. This comparison reveals: whether the threshold deflection 73 was exceeded; the level of the peak deflection 71; and the time after introduction of the process monitor 10 into the processing machinery at which the threshold 73 was exceeded. This enables the position in the processing machinery where damaging deflections 71, and therefore damaging loads 70, occur to be identified. The information so obtained can then be used to develop more efficient processing machinery. In some instances where the sugar beets proceed through the processing machinery at an uneven rate, it may be necessary for an observer to keep a timed record of progress of the process monitor. It will be realised that many alternative embodiments of the invention are possible. For example the electronic processing equipment 15 can be adapted: to monitor damaging deflection signals 74; to store in the solid state memory 19 within the electronic processing equipment 15, a discrete record 78 of damaging deflections signals 74 and the time at which the threshold deflection 73 was exceeded; and to display the record 78 and the time on a display 17 carried by the process monitor 10. Also it may be desired to obtain a continuous record of deflection 71 experienced throughout a process. Computerised systems for rapid data analysis and micro-electronic packs having telemetering or recording or storage capabilities, are well known in the art and hence not described in detail herein, can readily be adapted for use with the invention. It will also be realised that for the purposes of this specification the words conical and cylindrical, as applied to the core 12, or the head piece 24 are used to cover shapes other than those fulfilling the strict geometrical definitions. In other embodiments of the invention the piezo-electric plastic cables 14 can be laid on the core 12 in differing patterns. These alternative embodiments are illustrated as follows. A random pattern 32 is shown in Fig. 4, a distorted rectilinear pattern 34 is shown in Fig. 5, a helical pattern 36 is shown in Fig. 6, a unidirectional pattern 38 is shown in Fig. 7.

Claims: CLAIMS What is claimed is: 1. A package having physical characteristics simulating those of a product whose surface (40) is of substantially surface of revolution shape, and having at or adjacent to the surface (40) of the package a layer of piezo-electric material (42) which is connected to electronic processing equipment (15), characterised in that the surface (40) of the package forms an envelope (20) resembling a product with a length (46) to diameter (47) ratio greater than 2:1, the package being constructed so that deflections (71) sustained by the envelope (20) in response to bending loads (70) can be used to identify the occurrence of bending loads (70) which if applied to a product would cause damage. 2. A package as claimed in Claim 1 characterised in that the layer of piezo-electric material (42) is divided into strips (44) in adjacent to the surface (40) of the envelope (20), the strips (44) and the envelope (20) being arranged so that deflection signals (72), corresponding to deflections (71) of the envelope (20) experiencing bending loads (70), are produced by the strips (44) for collection by the electronic processing equipment (15) contained within the package. 3. A package as claimed in Claim 2 characterised in that the strips (44) are arranged in a helical pattern (36) conforming with the surface (40) of the envelope (20). 4. A package as claimed in Claim 2 characterised in that the strips (44) are arranged in a quasi unidirectional pattern (38) conforming with the surface (40) of the envelope (20), the strips (44) pointing in the direction of a longitudinal axis (45) of the envelope (20) and extending along the surface (40) of the envelope (20). 5. A package as claimed in Claim 2 characterised in that the strips (44) are arranged in a distorted rectilinear grid pattern (34) conforming with the surface (40) of the envelope (20). 6. A package as claimed in Claim 2 characterised in that the strips (44) are arranged in a random pattern pattern (32) conforming with the surface (40) of the envelope (20). 7. A package as claimed in any one of Claims 2 to 6 characterised in that the strips (44) are cables (14) formed from piezo-electric plastic material. 8. A package as claimed in any one of Claims 1 to 7 characterised in that the electronic processing equipment (15) is externally conditionable so that damaging deflection signals (74) are obtainable by triggering a pre-selected threshold deflection level (73) for the identification of bending loads (70) likely to damage the product being simulated. 9. A package as claimed in any one of Claims 1 to 8 characterised in that the processed deflection signals (75) are transmitted from the electronic processing equipment (15) to a data analysis means (76) capable of comparing the processed deflection signals (75) with a library of calibration signals (77) from the layer of piezo-electric material (42) compiled by the application of known bending loads (70) to the package, the comparison evaluating of the bending loads (70) experienced by the package. 10. A package as claimed in Claim 9 characterised in that the electronic processing equipment (15) has a storage means (19) for storing the deflection signals (72) or the damaging deflection signals (74) from the layer of piezo-electric material (42), the storage means (19) being accessible by the data analysis means (76) for interrogation of the deflection signals (72) or the damaging deflection signals (74) . 11. A package as claimed in Claim 9 or Claim 10 characterised in that the processed deflection signals (75) transmitted from the electronic processing equipment (15) to the data analysis means (76) are a discrete record 12. A package as claimed in Claim 9 or Claim 10 characterised in that the deflection signals (75) transmitted from the electronic processing equipment (15) to the data analysis means (76) are a continuous record (79) of deflection (71) against time. 13. A package as claimed in any one of Claims 9 to 12 characterised in that the data analysis means (76) is contained within the package and is connectable to a display means (17) carried by the package for displaying deflection records (78) (79) and times relating to the processing environment experienced by the package. 14. A package as claimed in any one of Claims 9 to 12 characterised in that the data analysis means (76) is a micro-computer (80) external to the package connectable to a display means (81) for displaying deflection records (78) (79) and times relating to the processing environment experienced by the package. 15. A package as claimed in Claim 14 characterised in that the data analysis means (76) is coupled directly to the electronic processing equipment (15). 16. A package as claimed in Claim 14 characterised in that the data analysis means (76) is coupled by telemetry to the electronic processing equipment (15). 17. A package as claimed in any one of Claims 1 to 16 characterised in that the material properties of the envelope (20) in the direction of the longitudinal axis (45) of the envelope (20) are chosen so as to permit deflection of the envelope (20) when the package encounters bending loads (70) . 18. A package as claimed in any one of Claims 2 to 17 characterised in that the material properties of the envelope (20) in a direction at right angles to the longitudinal axis (45) of the envelope (20) are chosen so as to transmit bending loads (70) applied to the envelope to the strips (44) whether the bending loads (70) are applied directly over a strip (44) or not. 19. A package as claimed in any one of Claims 1 to 16 characterised in that the envelope (20) includes a core (12) of substantially of circular cross-section with a circumferential surface (13), the material properties of the core (12) being chosen so as to permit the deflection (71) of the envelope (20) during the application of bending loads (70) to the package, the layer of piezo-electric material (42) being placed around the circumferential surface (13) of the core (12), and being supported between the circumferential surface (13) of the core (12) and an internal surface (41) of the envelope. 20. A package as claimed in Claim 19 characterised in that the core (12) is substantially conical and similar in shape to the product being simulated. 21. A package as claimed in Claim 19 characterised in that the core (12) is substantially cylindrical and similar in shape to the product being simulated. 22. A package as claimed in any one of Claims 1 to 21 characterised in that the package is similar in weight to that of the product being simulated. 23. A package as claimed in any one of Claims 1 to 21 characterised in that the package is similar in density to that of the product being simulated. 24. A package as claimed in any one of Claims 1 to 23 characterised in that the envelope (20) is constructed from re-inforced plastics composite material. 25. A package as claimed in any one of Claims 1 to 24 characterised in that the envelope (20) resembles the shape of a root of a sugar beet. 26. Processing machinery characterised in that it is developed with the aid of a package as claimed in any one of Claims 1 to 25. 27. A method of identifying a position of application of damaging bending loads to products passing through processing machinery characterised in that a package as claimed in any one of Claims 1 to 25 is included in a batch of products being processed by the machinery.

Inventors: BALLS ROGER, BARTLETT DAVID, WEAVER RICHARD, BALLS, ROGER, BARTLETT, DAVID, WEAVER, RICHARD
Applicants: BALLS ROGER, BARTLETT DAVID, MINI AGRICULTURE & FISHERIES, WEAVER RICHARD, BALLS, ROGER, BARTLETT, DAVID, THE MINISTER OF AGRICULTURE, FISHERIES AND FOOD IN, WEAVER, RICHARD
Application year: 1994
Main classification: G01L5
IPC codes: G01L5